ITEM 300 – AGGREGATE SURFACE COURSE

300.1 Description

This item shall consist of a wearing or top course composed of gravel or crushed aggregate and binder material, whichever is called for in the Bill of Quantities, constructed on a prepared base in accordance with this Specification and in conformity with the lines, grades, and typical cross-sections shown on the Plans.

300.2 Material Requirements

The aggregate shall consist of hard, durable particles or fragments of stone or gravel and sand or other fine material particles free from vegetable matter and lumps or balls of clay and of such nature that it can be compacted readily to form a firm, stable layer. It shall conform to the grading requirements shown in table 300.1 when tested by AASHTO T 11 and T 27.

Table 300.1 – Grading Requirements

Sieve Designation		Mass percent Passing
Standard,mm	Alternate US Standard	Grading A	Grading B	Grading C	Grading D
25 9.5 4.75 2.00 0.425 0.075	1” 3/8 No. 4 No. 10 No. 40 No. 200	100 50 – 85 35 – 65 25 – 50 15 – 30 5 - 20	100 60 –100 50 – 85 40 – 70 25 – 45 5 - 20	100 - 55 – 100 40 – 100 20 – 50 6 - 20	100 - 70 – 100 55 – 100 30 – 70 8 - 25

The course aggregate material retained on the 2.00 mm (No. 10) sieve shall have a mass percent of wear by the Los Angeles Abrasion Test (AASHTO T 96) of not more than 45.

When crushed aggregate is called for in the Bill of Quantities, not less than fifty (50) mass percent of the particles retained on the 4.75 mm (No. 4) sieve shall have at least one (1) fractured face.

The fraction passing the 0.075 mm (No. 200) sieve shall not be greater than two-thirds of the fraction passing the 0.425 mm (No. 40) sieve.

The fraction passing the 0.425 mm (No. 40) sieve shall have a liquid limit not greater than 35 and plasticity index range of 4 to 9, when tested by AASHTO T 89 and T 90, respectively.

Materials for gravel surface course and crushed aggregate surface course shall have a soaked CBR value of not less than 80% as determined by AASHTO T 193. The CBR value shall be obtained at the maximum dry density and determined by AASHTO T 180, Method D.

300.3 Construction Requirements

300.3.1 Placing

Aggregate surface course shall be placed in accordance with the requirements of Item 201, Aggregate Base Course.

300.3.2 Compacting Requirements

Aggregate surface course shall be compacted in accordance with the requirements of Item 201, Aggregate Base Course.

300.3.3 Trial Sections

Trial sections shall be carried out for aggregate surface course in accordance with the requirements of Item 201, Aggregate Base Course.

300.3.4 Surface Course Thickness and Tolerances

The aggregate surface course shall be laid to the designed level and transverse slopes shown on the Plans. The allowable tolerances shall be as specified hereunder:

Permitted variation from design                                +15 mm
THICKNESS OF LAYER                                          -5 mm

Permitted variation from design                                +15 mm
LEVEL OF SURFACE                                             -5 mm

Permitted SURFACE
IRREGULARITY                                                        5 mm
Measured by 3-m straight-edge

Permitted variation from design
CROSSFALL OR CAMBER                                      +0.2%

Permitted variation from design
LONGITUDINAL GRADE over 25 m in length      +0.1%

300.4 Method of Measurement

Aggregate surface course will be measured by the cubic meter (m3). The quantity to be paid for shall be the number of cubic meters of aggregate including all filler, placed, compacted and accepted in the completed course. No allowance shall be given for materials placed outside the design limits shown on the cross-sections. Trial sections shall not be measured separately but shall be included in the quantities measured above.

300.5 Basis of Payment

The accepted quantities, measured as prescribed in Section 300.4, shall be paid for at the contract unit price for Aggregate Surface Course which price and payment shall constitute full compensation for furnishing, handling, placing, watering and rolling all materials, including all labor and equipment, tools and incidentals necessary to complete this Item.

Payment will be made under:

Pay  Item Number	Description	Unit of Measurement
300 300 (1) 300 (2)	Aggregate Surface Course Gravel Surface Course Crushed Aggregate Surface Course	Cubic Meter compacted in place